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The 4D Printing Technique For Making Self-Assemble Objects

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Researchers at Singapore University of Technology and Design have developed a new 4d printing technique that can make complex structures in minutes. It can be used to create temperature-activated coronary stents, flat-pack furnitures, drug capsules and much more.

Zhen Ding with his colleagues, has found a unique way to quickly print rigid 4d objects with a 3d printer and a heat source.

So far, they have made a delicate flower that folds its petals, lattices that extend and contract, and a flat star shape that morphs into a dome. All these objects were created from flat 3d printed strips, which were later heated to a suitable temperature in order to alter their shape.

What Exactly Is 4D Printing?

4D printing uses the same approach of 3D printing, in which a special program deposit material in successive layers to build a 3D object. 4D printing, however, adds an extra dimension of transformation of object over time.

In other words, after the fabrication process, the 3D printed object reacts with external parameters like temperature, light or humidity, and alters its shape accordingly. The ability of changing structure depends on molecular spatial distributions of the material being used.

It is quite useful for creating objects that can adapt to environment, but is often an arduous process. Shape-memory polymers are the most common materials used in 4D printing and they typically require at least 5 steps to turn them into adaptable objects.

4D printing is evolving as a new paradigm in fields like material science, bioengineering, computer science and chemistry.

Direct 4D Printing Through Active Composite Substance

In this approach, strips are made from a layer of a stiff shape-memory polymer coupled with a rubbery elastomer. The shape-memory polymer enables the elastomer to be bent when heated to 45 degree Celsius. After a few moments when the strip gets cool, the shape-memory polymer stiffens again, giving object a new curved structure.

Reference: Direct 4D printing via active composite material

The only shortcoming of this approach is after on heating cycle, the configuration of the object could be altered again. It permanently fixes the structure when heated for the first time. This eliminates the applications that involve reversible shape changes such as prosthesis or robotic artificial muscles.

However, the technique can be successfully applied to build complex structures that do not need shape shifting, for instance, coronary stent – a tube-shaped device placed in blood vessels (heart) to keep them open. Coronary stent could open up in the artery, according to the internal temperature of the body. By adjusting temperature thresholds, medicine capsules could be bent and break open when body temperatures increases with infection. Moreover, flat-pack furniture could be self-assembled once heated.

In addition, it can be used to print a flat transformable sheet. Electronic and conductive devices like sensors, batteries and actuators can be easily assembled on the flat sheet. On heating, this flat structure could be converted into suitable 3d configuration with built-in electronic functionalities. One could also create smart flat substrate, with multiple polymers (having different behavior), and get a sequenced assembly operation.

Read: A New Metal 3d Printer | 100x faster and 10x cheaper

‘This technology can be easily used by people having different ideas – no new materials, equipment or chemistries are involved, so it is ready-to-use for everyone’ said Geoff Spinks at the University of Wollongong, Australia.